Boron-doped diamond modified with gold nanoparticles for the characterization of bovine serum albumin protein

Abstract

Boron-doped diamond (BDD) has been modified with bare gold nanoparticles (AuNPs) for the investigation of bovine serum albumin (BSA) protein films. First, the BDD electrode was amino-terminated via silanization with (3-aminopropyl)triethoxysilane (APTES). Then, the AuNPs were synthesized using a stainless steel-assisted method, and immobilized at the APTES-modified BDD surface (BDD/APTES/AuNPs). The resulting morphology of both modification steps was characterized using atomic force microscopy (AFM). Besides, the synthesis of AuNPs was in-situ monitored via infrared attenuated total reflection (IR-ATR) spectroscopy using a combined IR-ATR-EC-AFM system taking advantage of surface enhanced IR absorption (SEIRA) effects induced by the AuNPs. The modified conductive IR-ATR BDD waveguide was employed to investigate spectroelectrochemically films of globular and fibrilized BSA, which were deposited onto the AuNPs-modified surface. SEIRA spectroscopy enabled the discrimination between globular and fibril aggregates of BSA via curve fitting of amide I band revealing a major contributions of crossed β-sheet structures within the fibril aggregates. Finally, preliminary square-wave voltammetry experiments showed that the spectroelectrochemical setup has potential for in-situ electrochemical characterization of such protein films.